3000 Vrms isolation — the safety barrier that defines the fit
The Texas Instruments ISO7720FD is a two-channel, unidirectional digital isolator using capacitive coupling to provide 3000 Vrms galvanic isolation between input and output sides. It is a general-purpose device, meaning it is not tied to a specific protocol (like I²C or RS-485) but passes digital logic levels up to 100 Mbps. The 3000 Vrms rating is the primary spec that determines where this part goes: it meets the basic isolation requirements for industrial motor drives, power supplies, medical equipment, and telecom infrastructure where a 3 kV reinforced barrier is needed between a controller and a high-voltage domain.
100 Mbps data rate and 85 kV/µs CMTI — the throughput and noise immunity
The 100 Mbps data rate sets the maximum signal frequency the isolator can pass with a propagation delay of 16 ns (max) and a pulse-width distortion of 4.9 ns (max). This is fast enough for SPI buses, general-purpose GPIO isolation, and encoder interfaces, but not for high-speed serial links like Gigabit Ethernet. The 85 kV/µs common-mode transient immunity (CMTI) is the spec that matters in motor-drive and inverter applications: when the high-side voltage swings by hundreds of volts in a few nanoseconds, a low-CMTI isolator can latch or glitch. At 85 kV/µs, the ISO7720FD handles the transients typical in a 3-phase inverter bridge without corrupting the control signal.
The part is ROHS3 compliant and available in a standard 8-SOIC package, which is widely second-sourced across the isolator market if a dual-source strategy is needed.